diff --git a/data/apps/helpers.d/user b/data/apps/helpers.d/user
index 69f96e0cf..fc58d0027 100644
--- a/data/apps/helpers.d/user
+++ b/data/apps/helpers.d/user
@@ -1,6 +1,9 @@
 # Check if a user exists
 #
+# example: ynh_user_exists 'toto' || exit 1
+#
 # usage: ynh_user_exists username
+# | arg: username - the username to check
 # | ret: retcode - 0 if user exists, 1 otherwise
 ynh_user_exists() {
     sudo yunohost user list --output-as json | grep -q "\"username\": \"${1}\""
@@ -8,7 +11,11 @@ ynh_user_exists() {
 
 # Retrieve a user information
 #
-# usage: ynh_user_info username key
+# example: mail=$(ynh_user_get_info 'toto' 'mail')
+#
+# usage: ynh_user_get_info username key
+# | arg: username - the username to retrieve info from
+# | arg: key - the key to retrieve
 # | ret: string - the key's value
 ynh_user_get_info() {
     sudo yunohost user info "${1}" --output-as plain | ynh_get_plain_key "${2}"
diff --git a/data/apps/helpers.d/utils b/data/apps/helpers.d/utils
index 87cd47f6b..a6755e3c8 100644
--- a/data/apps/helpers.d/utils
+++ b/data/apps/helpers.d/utils
@@ -12,7 +12,7 @@ ynh_get_plain_key() {
             [[ "$line" =~ ^${prefix}[^#] ]] && return
             echo $line
         elif [[ "$line" =~ ^${prefix}${key}$ ]]; then
-            if [[ -n "$1" ]]; then
+            if [[ -n "${1:-}" ]]; then
                 prefix+="#"
                 key=$1
                 shift